I’m sure you’ve seen the chart, maybe on a poster at your gym or even right on the elliptical or treadmill. The one that shows you your target heart rate (using only your age) and that had the big red bars to highlight your “fat-burning zone”. The idea being that training in this zone is optimal for fat loss.

I kinda thought this myth was on the way out, especially with HIIT being the trend in fitness programming. But apparently, it’s still alive and well because it was just being talked about on a tv show I saw yesterday. 😐

Listen, I get why you would want this to be true if you have a weight loss goal: the idea that you could workout at a lower-intensity and burn more fat sounds pretty good, right?

Unfortunately it’s not that cut and dry…here’s why:

Your body’s multiple energy systems

Your body primarily uses carbohydrates and fats as fuel. For short, higher intensity activities that require energy quickly (anaerobic) for oxygen consumption, your body uses carbohydrates, as they’re more readily available (but are more limited).

When the activity requires more oxygen over a longer period of time (aerobic), your body switches to using fat as fuel, a process that takes longer but yields higher energy.

Since lower intensity exercise doesn’t need energy as fast, your body prefers oxidizing fat for fuel, which is in higher supply and can keep you going for a longer period of time.

At a lower intensity (50-70% of max heart rate), the percentage of calories burned from fat is higher…which would make you think that lower intensity/higher % burned from fat= greater fat loss!

Calories from fat vs. total calories

BUT. This is forgetting about the fact that when you’re exercising at a higher intensity (>70% of your max heart rate), the TOTAL number of calories you burn is higher.

So even though the number of calories burned from fat decreases as your intensity increases, the total calories burned is higher. More calories burned means a greater calorie deficit, which is necessary for fat loss.

Let’s redefine your fat-burning zone

If your goal is fat loss, but you don’t have (or want to) spend hours doing cardio, there are better ways to spend the time you do have that will be more effective in achieving your goal.

Instead of spending all of your time doing slow and steady cardio, do a combination of strength training and moderate/high intensity cardio sessions.

Strength training is effective for fat burning because 1) lean muscle requires more energy to maintain; the amount of muscle mass you have helps determine your resting metabolic rate (the calories your burn just by being), so more muscle means more calories burned AND 2) this means you’ll burn more calories even after your workout is over.

EPOC (excess post-exercise oxygen consumption) is the amount of oxygen required to restore your body back to its normal resting state. When you do higher intensity strength training that taxes your muscles, your body has to work harder to return to your resting metabolism. This means more energy (energy = calories) is used to get you back there.

So you might burn more calories doing a cardio workout vs. a strength workout, but that calorie burn continues long after your your strength workout is finished.

So I’m a little biased here, but I just want to take a second to talk about some of the other awesome benefits of strength training beyond fat-burning, because there’s SO MUCH more!

Especially for women in their 40s and beyond, strength training can:

-Help combat the loss of muscle mass that begins in your 30s and continues as you age

– Strengthen your bones and reduce your risk for osteoporosis (bone density also decreases as we age)

-Help you get stronger and make everyday life easier!

Ok, back to effective workouts for optimal fat loss…so in addition to the strength training that I’ve just convinced you needs to be part of your routine, include a mix of low, moderate and higher intensity cardio sessions.

Higher intensity workouts like interval training have been shown to burn more calories than lower intensity steady-state cardio (in less time!). However, I don’t recommend doing all high intensity because doing that puts you at higher risk for injury and/or burnout. Your body requires rest and recovery, so including low/moderate cardio workouts can give your body that chance to replenish your energy.

But also consider this…

As is the case with most instances when we’re talking about your health and fitness, there’s no ONE right way for everyone at all times. While I can make recommendations (and spread my love of strength training) it’s more important to me that you have the autonomy to do what works for you.

You will go through different stages and focus on different goals, which may require you to change up your activities. Also, remember that what may be an effective way of training for one person’s goals may not work for you, so it’s all about finding what fits for you!

Consider what your top priorities are. Obviously, we’ve been talking about fat loss as the primary goal in this post, but maybe what’s more important for you right now is to get consistent with exercise and make it a part of your regular lifestyle. (and losing some fat would be an added bonus).

What kind of exercise routine is more likely to help your achieve that goal? Is it easier for you to go out for a walk? Do you have access to strength training equipment? What do you actually like doing?

Lower intensity cardio activities may not be the most effective for optimal fat loss…but if you really enjoy them and you’re more likely to do that on a consistent basis, then by all means, do it!

Remember, no matter what your goal is…the most effective program is the one that you can actually do!

Consider any physical limitations you may have. Many of you are here because you’re a new (or newer) mom. High-intensity workouts that include lots of running or jumping or heavier strength training may not be appropriate at this stage depending on where you are in your postpartum experience.

You may only have the energy (both physical and mental) energy for lower intensity activities at this point. You may be experiencing symptoms of pelvic floor dysfunction that may require rehabilitation before progressing to higher intensity activities.

It’s important to consider, because even if you do have specific fitness or weight loss goals and you’re eager to start seeing results, pushing yourself past your current physical limits could end up actually setting you back!

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